Miranda Lambert treated her fans to an impromptu reunion of two-thirds of Pistol Annies at her concert in Knoxville on Thursday night (March 1). Lambert welcomed Ashley Monroe to the stage to join her on her hit, "Heart Like Mine."

Lambert performed at Thompson-Boling Arena in Knoxville, and she set Monroe's surprise appearance up with humor.

"So, I decided as a group family here in this room tonight, we should start a 'we need beer' campaign," Lambert tells the audience in the fan-shot video above, provoking a delighted roar of approval. "We need beer, right?" she asks rhetorically, raising a pink cup and adding, "Well, I'm gonna have one for all of you. Cheers, guys!"

"Speaking of beers," she says a moment later, "my best friend is here tonight with me, and she's from Knoxville, Tennesee, and we wrote a drinking song ... so welcome to the stage Miss Ashley Monroe, y'all!"

Miranda Lambert + Ashley Monroe Cover James Taylor

They split the verses and join their voices in harmony on the chorus of "Heart Like Mine," which gave Lambert her second No. 1 hit when it was released as the fifth single from Revolution in 2011. Lambert and Monroe co-wrote the song with Travis Howard, and the lyrics describe a strong, independent woman who feels that Jesus would understand her, despite some disapproval from family and friends.

"'Cause I heard Jesus he drank wine / And I bet we'd get along just fine / He could calm a storm and heal the blind / And I bet he'd understand a heart like mine," they sing in the chorus.

Lambert's comments prior to an acoustic performance of "Tin Man" that same night raised a fresh round of speculation about her relationship with singer-songwriter Anderson East amid rumors and reports that they have broken up.

"I want you to feel sad, mad, happy and nostalgic and really pissed sometimes. That's my favorite. And part of feelings is also heartbreak unfortunately, but fortunately for me, I can use it for my art or whatever. I like to write sad songs. I like to listen to sad songs, so I want to sing y'all one," she said, according to Knox News.

In Touch Weeklywas first to report a breakup, but there has been no confirmation. Lambert and East have not addressed the rumors publicly. Representatives for Lambert have not responded to Taste of Country's requests for comment, while East's declined to comment.

Monroe has just released a new single, "Hands on You," and she's set to release a new album titled Sparrow on April 20. Lambert hinted at a Pistol Annies reunion between her, Monroe and Angaleena Presley in January when she posted a photo on Instagram talking about a new song. She has since confirmed in an interview that they are working on new music, adding that "we're not close yet" to finishing a new project.

"Everybody is kind of in different directions, which is why the Annies always takes a while," Lambert says. "We're very much in the spirit of the Annies right now."